/*
 * Copyright (c) OSGi Alliance (2000, 2009). All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.osgi.framework;

import java.util.Dictionary;
import java.util.EventObject;

/**
 * An event from the Framework describing a service lifecycle change.
 * <p>
 * <code>ServiceEvent</code> objects are delivered to
 * <code>ServiceListener</code>s and <code>AllServiceListener</code>s when a
 * change occurs in this service's lifecycle. A type code is used to identify
 * the event type for future extendability.
 * <p>
 * <p>
 * OSGi Alliance reserves the right to extend the set of types.
 *
 * @version $Revision: 6542 $
 * @see ServiceListener
 */

public class ServiceEvent extends EventObject {
    static final long serialVersionUID = 8792901483909409299L;
    /**
     * Reference to the service that had a change occur in its lifecycle.
     */
    private final ServiceReference reference;

    /**
     * Type of service lifecycle change.
     */
    private final int type;

    /**
     * This service has been registered.
     * <p>
     * This event is synchronously delivered <strong>after</strong> the service
     * has been registered with the Framework.
     *
     * @see BundleContext#registerService(String[], Object, Dictionary)
     */
    public final static int REGISTERED = 0x00000001;

    /**
     * The properties of a registered service have been modified.
     * <p>
     * This event is synchronously delivered <strong>after</strong> the service
     * properties have been modified.
     *
     * @see ServiceRegistration#setProperties
     */
    public final static int MODIFIED = 0x00000002;

    /**
     * This service is in the process of being unregistered.
     * <p>
     * This event is synchronously delivered <strong>before</strong> the service
     * has completed unregistering.
     * <p>
     * <p>
     * If a bundle is using a service that is <code>UNREGISTERING</code>, the
     * bundle should release its use of the service when it receives this event.
     * If the bundle does not release its use of the service when it receives
     * this event, the Framework will automatically release the bundle's use of
     * the service while completing the service unregistration operation.
     *
     * @see ServiceRegistration#unregister
     * @see BundleContext#ungetService
     */
    public final static int UNREGISTERING = 0x00000004;

    /**
     * The properties of a registered service have been modified and the new
     * properties no longer match the listener's filter.
     * <p>
     * This event is synchronously delivered <strong>after</strong> the service
     * properties have been modified. This event is only delivered to listeners
     * which were added with a non-<code>null</code> filter where the filter
     * matched the service properties prior to the modification but the filter
     * does not match the modified service properties.
     *
     * @see ServiceRegistration#setProperties
     * @since 1.5
     */
    public final static int MODIFIED_ENDMATCH = 0x00000008;

    /**
     * Creates a new service event object.
     *
     * @param type      The event type.
     * @param reference A <code>ServiceReference</code> object to the service
     *                  that had a lifecycle change.
     */
    public ServiceEvent(int type, ServiceReference reference) {
        super(reference);
        this.reference = reference;
        this.type = type;
    }

    /**
     * Returns a reference to the service that had a change occur in its
     * lifecycle.
     * <p>
     * This reference is the source of the event.
     *
     * @return Reference to the service that had a lifecycle change.
     */
    public ServiceReference getServiceReference() {
        return reference;
    }

    /**
     * Returns the type of event. The event type values are:
     * <ul>
     * <li>{@link #REGISTERED} </li>
     * <li>{@link #MODIFIED} </li>
     * <li>{@link #MODIFIED_ENDMATCH} </li>
     * <li>{@link #UNREGISTERING} </li>
     * </ul>
     *
     * @return Type of service lifecycle change.
     */

    public int getType() {
        return type;
    }
}
